BSOD keeps occuring late at night

My machine keep getting BSOD between 11ish at night and 1 in the morning, often when I'm watching tv on it.
I've tried reinstalling software/drivers with no luck
I've run a memtest86+ over night and got 7 passes with no faults

I get IRQL_less_than_or_equalpage_fault_in_non_paged_area and bad_pool_caller as when my machine bluescreens

My system was fine, then after a recent XP reinstall the issues came, and after running stress tests and memtest I'm pretty sure my hardware is fine

I have uninstalled ZoneAlarm and run ccleaner to remove any trace, and reinstalled it, I'm not keen on not having a firewall. For the moment my system is stable, but I'll try to recreate the crash conditions this evening and see if the problem is sorted. Otherwise I'll try a different firewall

I understand about not wanting to go too long without a firewall. Two options that you might consider if ZA does not work out for you are COMODO (free and one of the best) or Online Armor (both free and $; also one of the best).

When reading minidumps they first give the error code with description of said error code and then below they will cite the problem as "Probably caused by:" and then give the faulting driver or hardware.

As for your error it is 0x50 which the same as before but again it could not read the faulting driver.

Question: Can you think of anything specific that you wer doing. i.e. gaming, net surfing, when these BSODs occur or is always at night between 11 and 1? Also, is any of your software scheduled for automatic updates at this specified period of time?

this one has occurred at 9pm, so it's not following the pattern
previously I've had BSOD while watching tv on my pc via channel4ondemand in their software or BBCiplayer through Firefox.
This time I was talking on msn when it cut out

You're welcome and I too hope its the end of your BSOD issues. I had Sunbelt's firewall at one time and through 5 different versions I kept getting BSODs due to the same driver over and over -- on two different PCs no less.

When I contacted their tech support and cited the driver they told me they knew about it but had no answer for it. True. I have their emails to prove it.

All it reported was an 0x50 error, it could not find the faulting drivers name, and a Windows OS driver was then cited as the probable cause and that is too general to be of any help.

I myself use NOD32 and Online Armor and I've never had conflicts with them except for some reason the Web Shield will kick me back to the Desktop and so I disabled that feature. otherwise everything is stable.

Can you remember what you were doing when this BSOD occured? if you get any more attach them.